$ git clone -n https://src.fedoraproject.org/rpms/ocaml-zarith.git /var/lib/mock/f39-build-2471521-61459/root/chroot_tmpdir/scmroot/ocaml-zarith
Cloning into '/var/lib/mock/f39-build-2471521-61459/root/chroot_tmpdir/scmroot/ocaml-zarith'...
$ git fetch origin a7b37c9b07b3ad5acb5d6aa0039bdc3cb6a375b3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ocaml-zarith
 * [new ref]         a7b37c9b07b3ad5acb5d6aa0039bdc3cb6a375b3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a7b37c9 Version 1.13